package com.sakura.apigateway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

import static org.springframework.web.cors.CorsConfiguration.ALL;

@SpringBootApplication
public class SakuraGatewayApplication {

    public static void main(String[] args) {
        SpringApplication.run(SakuraGatewayApplication.class, args);
        System.out.println("SakuraGateway==========网关启动成功==========");
    }

    private static final String MAX_AGE = "18000L";

    /***
     * @Description: 处理跨域请求
     * @return: org.springframework.web.server.WebFilter
     **/
    @Bean
    public WebFilter corsFilter(){
        return (ServerWebExchange ctx, WebFilterChain chain)->{
            ServerHttpRequest request=ctx.getRequest();
            if(!CorsUtils.isCorsRequest(request)){
                return chain.filter(ctx);
            }
            HttpHeaders requestHeaders=request.getHeaders();
            ServerHttpResponse response=ctx.getResponse();
            HttpMethod requestMethod=requestHeaders.getAccessControlRequestMethod();
            HttpHeaders headers=response.getHeaders();
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN,requestHeaders.getOrigin());
            headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS,requestHeaders.getAccessControlRequestHeaders());
            if(requestMethod!=null){
                headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());
            }
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS,"true");
            headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS,ALL);
            headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE,MAX_AGE);
            if(request.getMethod() == HttpMethod.OPTIONS){
                response.setStatusCode(HttpStatus.OK);
                return Mono.empty();
            }
            return chain.filter(ctx);
        };
    }

}
